The present invention relates to the recovery of symbol timing from an M-ary PSK (phase shift keyed) signal.
The recovery of symbol timing from a received M-ary PSK signal is necessary for detecting encoded bits. For recovering symbol timing from .pi./4-shift QPSK signals, one prior art technique employs a series connection of a frequency discriminator, a rectifier and a narrow-band filter. One shortcoming of this technique is that under low signal-to-noise ratio environments a threshold effect occurs both in the discriminator and rectifier. Another disadvantage is that the prior art circuitry is not amenable to integrated circuit technologies.